Near field inter-terminal communication or device-to-device communication (D2D communication) is a communication form in which a signal is directly transmitted between terminal devices, unlike a communication form in which a signal passes through a base station in cellular communication. Therefore, in the D2D communication, new use forms of terminal devices unlike the existing cellular communication are expected to appear. For example, various applications such as information sharing by data communication between near terminal devices or a group of near terminal devices, information distribution from installed terminal devices, and autonomous communication between devices called Machine Type Communication (MTC) can be considered.
With regard to the significant increase in data traffic with the recent increase of smartphones, the D2D communication can also be considered to be utilized in off-loading of data. For example, when terminal devices are in a state suitable for the D2D communication such as a case in which a distance between terminal devices is small, resource consumption and process loads in a Radio Access Network (RAN) can be suppressed by off-loading moving image data in the D2D communication. Thus, the D2D communication is useful for both communication providers and users. Therefore, at present, the D2D communication is recognized and noticed as one of the important technical areas necessary for Long Term Evolution (LTE) of the 3rd Generation Partnership Project (3GPP) standardization commission as well.
For example, as a technology related to D2D communication according to the same communication scheme as a communication scheme of cellular communication, a technology for Peer-to-Peer (P2P) communication between user equipments (UEs) according to Time Division-Code Division Multiple Access (TD-CDMA) is disclosed in Patent Literature 1.